In the manufacture of paper and paperboard and of products made from same, petroleum derived paraffin waxes and synthetic polymers have been used for many years as moisture retardants, water repellents, oil repellents, stiffeners, strengtheners, and release agents. Besides paraffin, the material used most often in such products is polyethylene. However, other widely used polymers in the field include polymerized acrylics, vinyls, styrenes, ethylenes and copolymers or hetero-polymers of these monomers. The paper and paperboard to which these traditional materials are applied is difficult and often impossible to repulp and recycle in standard paper mill processes because the petroleum derived polymers and, particularly, the petroleum waxes are non-biodegradable in mill white waters (circulated process waters) and discharge effluents. Furthermore, the residue of the petroleum waxes that is not removed from pulp fibers during the repulping and recycling processes causes severe problems due to buildup that occurs on the screens and felts used during the process of forming and making the paper or paperboard sheet. In addition, paper and paperboard coated or impregnated with petroleum waxes resist biodegradation and composting when disposed of in landfills and other waste disposal systems. Paper and paperboard coated or impregnated with traditional synthetic polymers and hetero-polymers are also difficult and often impossible to repulp and recycle owing to their resistance to separation from the fiber in the standard repulping processes resulting in significant fiber losses in efforts to repulp and recycle them, and these are also non-biodegradable and therefore resist composting.
Water repellent packaging currently utilizes petroleum based liquid polymers or polymer film laminates (including polyethylene or similar film laminates such as polyolefin, polyester, polyvinyl alcohol, polyvinyl acetate, polystyrene, polypropylene, and the like) which are recyclable after extensive treatment, All of these laminates require the installation of specialized repulping machinery that separates the pulp fibers from the laminated films and/or is far more expensive in terms of operating costs and/or recycled pulp fiber yields. The action of separating the fiber from the film damages some fibers causing them to be selected out of the recycled pulp and presented for reuse, and the separated film waste carries some of the fibers out of the repulpate when its adherence is not interrupted by the repulping process. Likewise, coatings and impregnating products made from or based on paraffin waxes and/or similar petroleum derivatives can be repulped for recycling in specially configured repulping equipment that removes and separates the paraffin waxes; however, as in the laminated film repulping process, the more intense physical and chemical requirements of this repulping process coupled with the lost fibers that become trapped in paraffin wax wastes cause the recyclable repulped fiber levels to fall far below those of standard repulping processes. Moreover, boxes made from such products are not biodegradable and must be separated and deposited in separate landfill areas.
The poultry box industry currently uses a wax to coat the boxes (EVA—poly (ethylene vinyl acetate) which takes a significantly long period of time to compost and leaves a chemical residue from those compounds. There appears to be little or no decomposition of higher molecular weight resin and EVA fractions.
In the prior art, a number of patents have attempted to address the above noted problem. U.S. Pat. No. 6,103,308 issued Aug. 15, 2000 is directed toward a paper and paperboard coating composition using vegetable oil triglyceride as a paper coating while U.S. Pat. No. 6,201,053 issued Mar. 13, 2001 is directed toward various triglycerides mixed with catalysts for use as a waterproofing agent on paper coating.
U.S. Pat. No. 6,846,573 issued Jan. 25, 2005 discloses the use of hydrogenated triglycerides having a melting point above 50° as a coating material for the surface of paper products to improve wet strength and moisture resistance in addition to being repulpable.
The use of tallow to treat paper is also well known in the prior art. U.S. Pat. No. 2,840,138 issued Jun. 24, 1958 discloses the use of tallow fatty acids to impregnate and penetrate corrugated paper material to provide a wilt resistant material. Also, U.S. Pat. No. 4,752,637 issued Jun. 21, 1988 is directed to a method of treating fiberboard to have superior moisture resistance with various mixtures of hydroxy terminated esters such as tallow.
None of the noted references have provided a repulpable, recyclable corrugated box capable of holding iced products and being moisture resistant.